Adipic acid is an important commodity in the chemical industry, particularly for consumption as a comonomer in the synthesis of polymers. Adipic acid is obtained by oxidation of cyclohexane or cyclohexanol on a commercial scale.
Indicative of the volume of adipic acid directed to polymer production, in 1980 the market for nylon 6,6 was about 1.5 billion pounds. A monomer precursor for nylon 6,6 is a 50% aqueous solution of "nylon 6,6 salt", which is an ionic combination of adipic acid and hexamethylenediamine: ##STR1## Hexamethylenediamine can be derived from adipic acid via amide and nitrile intermediates.
There is continuing research effort to develop new and improved processes for the production of commodity chemicals such as adipic acid and hexamethylenediamine.
One prospective method for synthesis of adipic acid is by the hydrogenation of muconic acid, which is a diolefinically unsaturated adipic acid derivative: ##STR2##
A potentially convenient source of muconic acid is by the microbiological oxidation of various hydrocarbon substrates. Microbiological oxidation of hydrocarbons is reviewed in Applied Microbiology, 9(5), 383(1961) and in "Advances in Enzymology", 27, 469-546(1965) by Interscience Publishers. The prospect of biotechnical methods for commercial scale production of commodity chemicals is under active investigation.
Accordingly, it is an object of this invention to provide a process for production of muconic acid by microbiological oxidation of a hydrocarbon substrate.
It is another object of this invention to provide a novel process for the production of nylon 6,6 salt which involves a microbiological fermentation step.
It is a further object of this invention to provide a process for production of adipic acid and hexamethylenediamine.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.